Lifting-jack.



J. 0. ST. PIERRE LIFfI'ING JACK. APPLICATION FILED SEPTA, 1012.

2 SHEETS$HEET l.

W mwmw: %,4 W ww mwflww Patented Mar. 9, 1915.

J. 0. ST. PIERRE.

LIFTING JACK.

APPLICATION FILED SEPT. 4, 1912.

mmmw Patented Mar. 9, 11915.

2 SHEETSSHEET 2,

M w w- Q maintain s r-arias JOSEPH 0. ST. PIERRE, 015 BOSTON, MASSACHUSETTS.

LIFTING-J'ACK.

and perfect the type of quick action, self lowering jack described' and claimed in a pending application filed by me on March 4th, 1912, Serial No. 681,661, and in which a supplemental train of spur gears were connected by ratchet mechanism to the mam operating gear spindle so that they would be rotated by the latter when driven in a reverse direction to that taken by it in raising. the jack. The supplemental train of gearing was given a sufficiently high ratio of speed reduction to cause its inertia to substantially retard and brake the descent of the jack under its load and a freely controllable manual brake was applied at the high speed end of the supplemental gearing and was suflicient to perfectly control the descent of the jack without jarring or injury thereto under maximum loads.

My present invention relates to an improvement in the design and arrangement of this supplemental gearing and consists essentially in the substitution for a large part of reduction spur gearing of a worm and worm wheel, the threads of which are so pitched that the jack will start the descent under its own load automatically when the brake is released and this worm and worm wheel serve not only to increase the holding power .of the brake but also to reduce the size and simplify the construction of a gearing having a ratio of speed reduction sufficiently high to meet the ends above set forth.

The invention further consists in certain novel features of construction and arrange ment of parts which will be fully understood by reference to the description of theadrawings and to the claims hereinafter given.

Of the drawings: Figure 1 represents a horizontal section of a lifting jack embodying the features of this invention, the cutting plane being on line 1-1 on F ig. 2. Fig. 2 represents a vertical section of the same, the cutting plane being on line 22 on Fig.

Specification of Letters Patent.

Application filed September 4-, 1912. Serial No. 718,757.

1. Fig. 3 represents an enlarged section of the removable plate, the cutting plane being on line 33 on Fig. 2, and showing in elevation the mechanisms for retarding or ar resting the movement of the jack lowering mechanism, and Fig. 4 represents an elevation of the device for applying friction to said rotatable member.

Similar characters designate like parts throughout several figures of the drawmgs. W

In the drawings, 10 represents a suitable base supporting a stationary standard 11 over the outer periphery of which is fitted, a movable sleeve 12, to the upper end ofwhich is threaded a cap 13. In the upper end of the standard 11 is mounted a nut 1a to which is threaded a lifting screw 15 having splined to its upper reduced end a gear 16 with which meshes a gear 17 formed upon or secured to a revoluble shaft or spindle 18,

the outer end of which is provided with a suitable operating mechanism 19 of any well-known construction. Tn'terposed between the upper face of the gear 16 and the inner face of the cap 13 are two annular plates 20 and 21, between which are interposed a plurality of antifriction members 22.

Secured to the gear 17 by means of the screws 19 is a ratchet 22 with the teeth of which engage a plurality of spring pressed pawls 23 pivotally secured to a spur gear 24- freely revoluble and'mounted upon a re duced portion 25 of the cylindrical hub 26 forming a bearing for said spindle or shaft 18. This hub 26 is formed integral with a removable plate 25 secured to the flanged projection 28 forming a part of the movable member 12. The gear 24 meshes with a pinion 29 secured to or formed integral with a revoluble member 30 to which. is also secured a gear 31 meshing with a pinion 32 formed upon or secured to a revoluble member 33 to which is also secured a worm gear 34-. This worm gear 3 1- meshes with a worm 35 secured upon a shaft 36 and interposed between the lugs 37 secured to the plate 27 and in which said shaft 36 is provided with bearings. The pitch of the worm 35 is such that during the rotation of the worm gear 34 rotary movement will be imparted to the shaft 36. This shaft 36 has secured to its outer end a friction disk 38 the periphery of which is preferably tapered as indicated in Fig. 3 of the drawings and is adapted to have friction applied. thereto by means of its spindle 18.

the friction member 39 secured to the threadedstud 40 extending through lugs 41 formed upon the sleeve 12. Threaded to thestud 40 and interposed between the lugs 41 1s a nut 42 adapted to be rotated by hand to move the friction member 39 into and from contact with the friction disk 38. I

In the operation of the device when it IS desired to raise the movable member 12 the operating mechanism 19- is manipulated to .turn the spindle 18 and gear 17 formed thereon in the direction of the arrow at on Fig. 3 ofthe drawings. When this is done the-ratchet 22 will freelypass the pawls 23 without disturbing the train of gearing adapted during the lowering of the jack to be actuated by the driving gear 24: to which the pawls 23 are pivotally secured. During this operation the friction member 39 maybe in contact with the friction disk 38 or not as desired. It is obvious, therefore, that during the operation of the jack to 11ft a load the operating mechanism 19 will act directly upon the movable member 12 through the gears 17 and 16 and screw '15 without affecting in any manner the operation of the train of gearing hereinbefore mentioned.

When the weight has been lifted suffielevated position the nut 42 may be manually operated to bring the friction member 39 into frictional contact with the rotatable member 38 and all movement of the said train of gears will be effectually prevented thereby resisting the tendency of saidload to actuate this train by the rotation of the spindle 18 in a direction opposite to that indicated by the arrow a on Fig. 3, thereby causing the engagement of the teeth ofthe ratchet wheel 22 and the pawls 23. When it is desired to lower the movable member 12 the friction member 39 may be removed from the rotatable member 38 and with the pawls 23 in engagement with the teeth of the ratchet 22 the train of gearing will be driven by the rotation of the gear 117 and The pitch of the worm threads are such as to permit the jack to start automatically to descend under its own load when its brake is released. This train of gearing is geared up to such an extent that the shaft 36 and the rotatable member 38 rotate very rapidly, while the inertia of the gearing acts to substantially retard and prevent excessive speed in the descent of the jack. Should an excessive load be upon the cap 13 so that the member 12 ciently and it is desired to retain it in its. I

into contact therewith the friction member.

39, the multiplication of the braking power through the high ratio gearing and through the worm and worm wheel serving to make possible the quick and easy stoppage, by hand or by a light pressure of the brake, of the descending jack at any point. It is quite obviousthat when this friction member 39 is in contact with the rotatable member 38 the rotation of the spindle 18 will be controlled during the lowering of the jaekf through a train of gearing or may be arrested completely while during the lifting operation these mechanisms are entirely unaffected by the rotation of said spindle 18.

It is selfevident that with the mechanism described an accidental lowering of the jack iswhollyv obviated and Whenever it becomes necessary to lower the jack quickly it may beaccomplished with any degree of rapidity desired.

It is believed that the operation and many advantages ofthe invention will be fully understood from the foregoing description.

Having thus described my invention, I claim:

In a quick action self lowering jack, the combination of a stationary member, a movable member, a revoluble member for raising and lowering said movable member, a shaft, a gearing having a low ratio of speed reduction and serving as a driving connection between said shaft and revoluble member, a second train of gearing comprising a train of spur gears designed and arranged to afford a high ratio of speed multiplication and a worm gearing connected at the high speed end of said train of. spur gears, said worm gearing comprising a worm wheel and a worm having its threads pitched to permit the jack to start automatically to descend under its own'load when its'brake isrelased, a pawl and ratchet drive between the low speed end of said train of spur gears and said shaft which automatically disconnect thespur gears from the shaft when the latter is turned to lift the jack, and a friction brake means driven by the worm, substantially as described.

Signed by me at 1 Post Ofii'ce Sq., Boston, Mass, this 30th day of August, 1912.

- JOSEPH 0. ST. PIERRE. Witnesses:

WALTER E. LOMBARD, NATHAN C. LOMBARD.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. 0." 

